Hyperbranched Polyether Polyol and Urethane Resin Composition

ABSTRACT

A hyperbranched polyether polyol obtained by a ring-opening reaction between a hydroxyalkyloxetane (a1) and a monofunctional epoxy compound (a2), wherein the polyether polyol includes a primary hydroxyl group (H1) and a secondary hydroxyl group (H2) in the molecular structure thereof, and has a number average molecular weight (Mn) of 1,000 to 4,000 and a hydroxyl value of 150 to 350 mg·KOH/g.

TECHNICAL FIELD

The present invention relates to a hyperbranched polyether polyol and aurethane resin composition.

BACKGROUND ART

Urethane resin compositions formed from a polyol component and apolyisocyanate component have been widely used as a covering material orthe like, which is usable for a floor member or the like of anarchitectural member, since the urethane resin compositions havecharacteristics such that they are excellent in curability and excellentin elongation of a cured film obtained from the urethane resincomposition. However, there are problems in that cured products obtainedfrom the urethane resin compositions are generally soft, and theappearance of a coated film thereof is poor since the coated film iseasily foamed due to moisture absorption thereof. Accordingly, in recentyears, various studies for improving a hard type urethane resincomposition have been conducted (for example, Patent Document 1).

On the other hand, in order to improve the hardness of a coveringmaterial, increasing the reactivity of a polyol component and apolyisocyanate component has been accomplished in general. However, whenthe reactivity is too high, there are problems in that sufficient potlife is not obtained, that is, a sufficient period, wherein a preparedresin composition is maintained in useable condition without beingcured, is not obtained, since said components react to each otherspeedily once both components are mixed.

Therefore, it has been known conventionally that a hard type urethaneresin composition, which can be used for a covering, ensures asufficient pot life, and generates minimal foam even under conditions ofhigh temperature and high humidity, can be prepared by using a mixture,in which of a castor oil fatty acid and a polyol having a structurewherein a higher fatty acid is reacted with a bisphenol type epoxy resinare mixed, as a polyol component, and a mixture, in whichdiphenylmethane diisocyanate (abbreviated to MDI) and polymethylenepolyphenyl polyisocyanate (abbreviated to polymeric MDI) are mixed in apredetermined ratio, as polyisocyanate components (refer to PatentDocument 2 shown below).

The aforementioned technique, wherein a mixture of a castor oil fattyacid and a polyol having the structure in which higher fatty acid isreacted with a bisphenol type epoxy resin is used as a polyol component,and a mixture of MDI and polymeric MDI which are mixed in apredetermined ratio are used as a polyisocyanate component, ensures along pot life and the formation of a hard coating. However, due to theremarkably high viscosity of the polyol component included in theurethane resin composition, it is hard for the technique to be adoptedto coating methods such as brush coating, roller coating and spraycoating, which can be conducted without skill and do not generate spotson the finished surface after coating.

Furthermore, a polyurethane resin which uses a diol prepared bycopolymerizing an oxetane compound with tetrahydrofuran has been known.However, the resin does not ensure a sufficient pot life nor highhardness (refer to Patent document.)

Patent Document 1: Japanese Unexamined Patent Application, FirstPublication No. Sho 57-92015

Patent Document 2: Japanese Unexamined Patent Application, FirstPublication No. 2001-187863 Patent Document 3: Japanese UnexaminedPatent Application, First Publication No. 2004-149771 DISCLOSURE OFINVENTION Problems to be Solved by the Invention

Subjects to be achieved by the present invention are to provide a newpolyether polyol which has remarkably low viscosity and can ensure asufficient pot life and provide high hardness to a cured film when it isused as at least one constituent of a polyol component of a urethaneresin composition; and to provide a urethane resin composition whichcomprises the aforementioned polyether polyol and is excellent incoating hardness and workability.

Means for Solving the Problems

The inventors of the preset invention studied and made every effort toachieve the above subjects. As a result, they found a compound and aurethane resin composition including the compound and achieve thepresent invention, wherein the compound and the composition are possibleto increase a pot life of the urethane resin composition, achieve highhardness of a film obtained from the composition due to increasedcrosslinking density at the time of curing, and achieve low viscosity ofthe urethane resin composition due to small inertia radius of thecompound. The urethane resin composition includes the compound as apolyol component, wherein the compound has a hyperbranched structureobtained by copolymerizing a hydroxyalkyloxetane and a monofunctionalepoxy compound by ring-opening reaction, the compound has a primaryhydroxyl group and a secondary hydroxyl group, and furthermore thecompound has a predetermined average molecular weight and apredetermined total hydroxyl value.

That is, the present invention provides a hyperbranched polyether polyolobtained by a ring-opening reaction between a hydroxyalkyloxetane (a1)and a monofunctional epoxy compound (a2), wherein the polyether polyolincludes a primary hydroxyl group (H1) and a secondary hydroxyl group(H2) in the molecular structure thereof, and has a number averagemolecular weight (Mn) of 1,000 to 4,000 and a hydroxyl value of 150 to350 mg·KOH/g.

Furthermore, the present invention relates to a urethane resincomposition which comprises a polyol component (A) and a polyisocyanatecomponent (B) as essential components, and the aforementionedhyperbranched polyether polyol is used as the polyol component (A).

EFFECTS OF THE INVENTION

Due to the present invention, it is possible to provide a polyetherpolyol which can ensure a sufficient pot life, provide high hardness toa cured film and greatly decrease the mixture viscosity of a resincomposition, when the polyether polyol is used as a polyol component ofa urethane resin composition. Furthermore, the urethane resincomposition which includes the polyether polyol can achieve bothexcellent workability and coating hardness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chart of ¹³C-NMR of a hyperbranched polyether polyolobtained in Example 1.

FIG. 2 is a chart of proton NMR of a hyperbranched polyether polyolobtained in Example 1.

FIG. 3 is a chart of ¹³C-NMR of a hyperbranched polyether polyolobtained in Example 2.

FIG. 4 is a chart of proton NMR of a hyperbranched polyether polyolobtained in Example 2.

FIG. 5 is a chart of ¹³C-NMR of a hyperbranched polyether polyolobtained in Example 3.

FIG. 6 is a chart of proton NMR of a hyperbranched polyether polyolobtained in Example 3.

FIG. 7 is a chart of ¹³C-NMR of a hyperbranched polyether polyolobtained in Example 4.

FIG. 8 is a chart of proton NMR of a hyperbranched polyether polyolobtained in Example 4.

FIG. 9 is a chart of ¹³C-NMR of a hyperbranched polyether polyolobtained in Example 5.

FIG. 10 is a chart of proton NMR of a hyperbranched polyether polyolobtained in Example 5.

FIG. 11 is a chart of ¹³C-NMR of a hyperbranched polyether polyolobtained in Example 6.

FIG. 12 is a chart of proton NMR of a hyperbranched polyether polyolobtained in Example 6.

FIG. 13 is a chemical formula which shows an example of a hyperbranchedpolyether polyol generated in the present invention.

FIG. 14 is a chemical reaction formula which shows an example offormation of a hyperbranched polyether polyol of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention is explained in detail usingpreferable examples. However, the present invention is not limited onlyto the following examples.

A hyperbranched polyether polyol of the present invention is ahyperbranched polyether polyol which can be obtained by a ring-openingreaction between a hydroxyalkyloxetane (a1) and a monofunctional epoxycompound (a2). In the present invention, it is assumes that thehyperbranched polyether polyol has the structure described above, andtherefore, the radius of gyration of the hyperbranched polyether polyolis small and tangles between molecules thereof are small, and as theresult, the mixture viscosity of the urethane resin composition candecrease. Here, “hyperbranched” described in the present invention meansthat the molecular structure has a branched structure which is furtherbranched at the branched terminal end.

Any hydroxyalkyloxetane compound can be used as the hydroxyalkyloxetane(a1) used in the present invention, in so far as problems are notcaused. The hydroxyalkyloxetane (a1) can be used singly or incombination of two or more. For example, a compound having the structurerepresented by the following formula (1) can be cited as an example ofthe hydroxyalkyloxetane (a1).

Here, in the general formula (1), R₁ represents a methylene group, anethylene group or a propylene group, and R₂ represents a hydrogen atom,an alkyl group having 1 to 8 carbon atoms, an alkoxyalkyl group having 1to 5 carbon atoms or a hydroxyalkyl group having 1 to 6 carbon atoms.Examples of the alkyl group having 1 to 8 carbon atoms include a methylgroup, an ethyl group, an n-propyl group, an i-propyl group and a2-ethylhexyl group. Examples of the alkoxyalkyl group having 1 to 5carbon atoms include a methoxymethyl group, an ethoxymethyl group, apropoxymethyl group, a methoxyethyl group, an ethoxyethyl group and apropoxyethyl group. Examples of the hydroxyalkyl group having 1 to 3carbon atoms include a hydroxymethyl group, a hydroxyethyl group and ahydroxypropyl group.

Among the examples of the hydroxyalkyloxetane (a1) represented by thegeneral formula (1), a compound wherein R₁ represents a methylene groupand R₂ represents an alkyl group having 1 to 7 carbon atoms arepreferable because high hardness of a cured product can be achieved andviscosity can be reduced effectively due to the small radius of gyrationthereof. Among the examples, 3-hydroxymethyl-3-ethyloxetane and3-hydroxymethyl-3-methyloxetane are especially preferable.

Any monofunctional epoxy compound can be used as the monofunctionalepoxy compound (a2), which is used for a ring-opening reaction with thehydroxyalkyloxetane (a1), in so far as problems are not caused. Themonofunctional epoxy compound (a2) can be used singly or in combinationof two or more. Examples thereof include an olefin epoxide, a glycidylether compound and a glycidyl ester compound.

The olefin epoxide is not limited in particular. Concrete examplesthereof include propylene oxide, 1-butene oxide, 1-pentene oxide,1-hexene oxide, 1,2-epoxy octane, 1,2-epoxy dodecane, cyclohexene oxide,cyclooctene oxide, cyclododecene oxide, styrene oxide, and fluoroalkylepoxide having 1 to 18 fluorine atoms.

The glycidyl ether compound is not limited in particular. Concreteexamples thereof include methyl glycidyl ether, ethyl glycidyl ether,n-propyl glycidyl ether, i-propyl glycidyl ether, n-butyl glycidylether, i-butyl glycidyl ether, n-pentyl glycidyl ether, 2-ethyl hexylglycidyl ether, undecyl glycidyl ether, hexadecyl glycidyl ether, arylglycidyl ether, phenyl glycidyl ether, 2-methyl phenyl glycidyl ether,4-t-butyl phenyl glycidyl ether, 4-nonyl phenyl glycidyl ether,4-methoxy phenyl glycidyl ether and fluoroalkyl glycidyl ether which has1 to 18 fluorine atoms.

The glycidyl ester compound is not limited in particular. Concreteexamples thereof include glycidyl acetate, glycidyl propionate, glycidylbutyrate, glycidyl methacrylate and glycidyl benzoate.

Among these compounds, olefin epoxide is preferably used since highcoating hardness can be achieved and molecular weight of thehyperbranched polyether polyol can decrease. Propylene oxide, 1-buteneoxide, 1-pentene oxide and 1-hexene oxide are particularly preferable.

Any method can be used for conducting the ring-opening reaction whereina hydroxyalkyloxetane (a1) and a monofunctional epoxy compound (a2) areused for raw materials, in so far as problems are not caused. Concreteexamples thereof include the following methods (1) to (4). Theconditions of the methods can be changed if necessary.

(Method 1)

A hydroxyalkyloxetane (a1) and a monofunctional epoxy compound (a2) asraw material components are mixed in a ratio (molar basis) of ahydroxyalkyloxetane (a1) to a monofunctional epoxy compound (a2) is 1:1to 1:10, preferably 1:1 to 1:6 and more preferably 1:1 to 1:3. Theprepared mixture is mixed and dissolved in an organic solvent, whichdoes not include peroxide, such as diethyl ether, di-i-propyl ether,di-n-butyl ether, di-i-butyl ether, di-t-butyl ether, t-amyl methylether, t-butyl methyl ether, cyclopentyl methyl ether or dioxolane, sothat the mass ratio of raw material components ((a1)+(a2)) to an organicsolvent is 1:1 to 1:5, preferably 1:1.5 to 1:4 and more preferably 1:1.5to 1:2.5 to prepare a raw material solution.

The obtained raw material solution is cooled, preferably to −10 to −15°C., while it is stirred. Next, a polymerization initiator is addeddropwise as it is or in a state of a solution which includes thepolymerization initiator, to the cooled raw material solution whilebeing stirring over 0.1 to 1 hours, preferably 0.3 to 0.8 hours and morepreferably 0.3 to 0.5 hours. The polymerization initiator can be used ina ratio of 0.01 to 0.6 mol %, preferably 0.05 to 0.55 mol % and morepreferably 0.2 to 0.5 mol % based on the total mass of raw materialcomponent monomers. Furthermore, when the polymerization initiator isused in a state of a solution which includes the polymerizationinitiator, the concentration of the polymerization initiator in thesolution is preferably 1 to 90% by mass, more preferably 10 to 75% bymass and still more preferably 25 to 65% by mass. Subsequently, the rawmaterial solution to which the polymerization initiator is added isstirred until the temperature becomes 25° C. Then, the solution isheated to a temperature at which the solution is refluxed, and apolymerization reaction is performed over 0.5 to 3 hours until all rawmaterial component monomers have been reacted. The conversion of the rawmaterial component monomers can be controlled by analyzing GC, NMR or IRspectrum.

After the polymerization reaction is completed, the obtained polymersolution is neutralized by adding sodium alkoxide or potassium alkoxidewhich is equivalent to the aforementioned polymerization initiator, orby stirring with an alkali hydroxide solution which is equivalent to theaforementioned polymerization initiator. After the neutralization,filtration is conducted, and then a hyperbranched polyether polyol,which is a target material, is extracted with a solvent. Subsequently,distillation of the solvent is conducted under reduced pressure toobtain a hyperbranched polyether polyol which is a target material.

(Method 2)

A polymerization initiator is dissolved in an organic solvent so thatthe amount of the polymerization initiator is 0.1 to 5 mol %, preferably0.2 to 3.5 mol % and still more preferably 0.25 to 1.0 mol % based onthe total molar amount of raw material component monomers. Here, theorganic solvent is preferably an organic solvent which does not includeperoxide, such as diethyl ether, di-i-propyl ether, di-n-butyl ether,di-i-butyl ether, di-t-butyl ether, t-amyl methyl ether, t-butyl methylether, cyclopentyl methyl ether or dioxolane. The organic solvent can beused in the mass ratio such that total mass of raw material componentmonomers to the mass of an organic solvent is 1:0.25 to 1:5, preferably1:0.3 to 1:3.5 and more preferably 1:0.5 to 1:2.

A mixture is prepared wherein a hydroxyalkyloxetane (a1) and amonofunctional epoxy compound (a2) are mixed in a ratio (molar basis) ofa hydroxyalkyloxetane (a1) to a monofunctional epoxy compound (a2) is1:1 to 1:10, preferably 1:1 to 1:6 and more preferably 1:1 to 1:3. Thepolymerization initiator solution is maintained at a temperature of 10to 60° C., and the prepared mixture is added to the polymerizationinitiator solution dropwise while it is stirred over 0.1 to 20 hours,preferably over 2 to 10 hours. After the addition is completed, apolymerization reaction is performed at a temperature of 20 to 60° C.until all raw material component monomers have been reacted to form ahyperbranched polyether polyol. After the reaction is completed,neutralization and filtration are conducted similar to the Method 1, anddistillation of the solvent is conducted to obtain a hyperbranchedpolyether polyol which is a target material.

(Method 3)

A hydroxyalkyloxetane (a1) and a monofunctional epoxy compound (a2) aredissolved in a hydrocarbon type solvent, which has a boiling point of70° C. or more, to prepare a solution, so that the hydroxyalkyloxetane(a1) and the monofunctional epoxy compound (a2) are included in a ratio(molar basis) of a hydroxyalkyloxetane (a1) to a monofunctional epoxycompound (a2) is 1:1 to 1:10, preferably 1:1 to 1:6 and more preferably1:1 to 1:3. Examples of the hydrocarbon type solvent include n-heptane,i-octane and cyclohexane. From the viewpoint of solubility, cyclohexaneis preferably used. The ratio (mass ratio) of raw material componentmonomers to a hydrocarbon type solvent is preferably such that the ratioof raw material component monomers to a hydrocarbon type solvent is 1:1to 1:10, more preferably 1:2 to 1:7 and still more preferably 1:2.5 to1:3.5.

The obtained mixed solution is maintained at a temperature of 0 to 25°C., preferably 5 to 15° C. and still more preferably 10 to 15° C., andthen a polymerization initiator, which is 0.01 to 1 mol %, preferably0.03 to 0.7 mol % and still more preferably 0.05 to 0.15 mol % based onthe total amount of the raw material component monomers, is added atonce to the solution while it is stirred.

Immediately after the polymerization initiator is added, the inside ofthe system is ununiform and the temperature in the system increases to25 to 40° C. After the solution is cooled to 15 to 25° C., the obtainedreaction mixture is heat to 40 to 70° C., more preferably 50 to 60° C.,and the reaction is performed for 1 to 5 hours, more preferably 2 to 3hours, until all raw material component monomers are reacted to form ahyperbranched polyether polyol. After the reaction is completed,neutralization and filtration are conducted similar to the Method 1, andthen, distillation of the solvent is conducted to obtain a hyperbranchedpolyether polyol which is a target material.

(Method 4)

A polymerization initiator is dissolved in an a hydrocarbon type organicsolvent, which has a boiling point of 70° C. or more, so that the amountof the polymerization initiator is 0.01 to 1 mol %, preferably 0.025 to0.7 mol % and still more preferably 0.05 to 0.15 mol % based on thetotal amount of raw material component monomers. The obtained solutionis maintained at a temperature of 0 to 25° C., preferably 5 to 15° C.and still more preferably 10 to 15° C. Examples of the hydrocarbon typesolvent include n-heptane, i-octane and cyclohexane. From the viewpointof solubility, cyclohexane is preferably used. The concentration of thepolymerization initiator in the hydrocarbon type solvent is preferably0.01 to 1 mass %, more preferably 0.15 to 0.7 mass % and still morepreferably 0.025 to 0.25 mass %.

In the polymerization initiator solution, a mixture in which ahydroxyalkyloxetane (a1) and a monofunctional epoxy compound (a2) aremixed in a ratio (molar basis) of a hydroxyalkyloxetane (a1) to amonofunctional epoxy compound (a2) of 1:1 to 1:10, preferably 1:1 to 1:6and more preferably 1:1 to 1:3, is added successively and dropwisely sothat a temperature in the system is 20 to 35° C.

After the addition is completed, stirring is continued until thetemperature in the system becomes 20 to 25° C. Subsequently, thereaction mixture is heated to 40 to 70° C., more preferably 50 to 60°C., and a polymerization reaction is performed for 1 to 5 hours,preferably 2 to 3 hours, until all raw material component monomers havebeen reacted. The conversion of the raw material component monomers canbe controlled by analyzing GC, NMR or IR spectrum. After the reaction iscompleted, neutralization and filtration are conducted similar to in theMethod 1, and then, distillation of the solvent is conducted to obtain ahyperbranched polyether polyol which is a target material.

As the polymerization initiator usable in the present invention, anypolymerization initiator can be used as long as problems are not caused.Examples of the polymerization initiator include: bronsted acids such asH₂SO₄, HCl, HBF₄, HPF₆, HSbF₆, HAsF₆, p-toluenesulfonic acid andtrifluoromethane sulfonic acid; lewis acids such as BF₃, AlCl₃, TiCl₄and SnCl₄; onium salt compounds such as triarylsulfonium-hexafluorophosphate, triarylsulfonium antimonate, diaryl iodonium-hexafluorophosphate, diaryl iodonium-antimonate, n-benzyl pyridinium-hexafluorophosphate and n-benzyl pyridinium-antimonate; triphenyl carbonium saltssuch as triphenyl carbonium-tetrafluoro borate, triphenylcarbonium-hexafluoro phosphate and triphenyl carbonium-hexafluoroantimonite; alkylating agents such as p-toluenesulfonyl chloride,methanesulfonyl chloride, trifluoromethanesulfonyl chloride,p-toluenesulfonic anhydride, methanesulfonic anhydride,trifluoromethanesulfonic anhydride, p-toluenesulfonic acid methyl ester,p-toluenesulfonic acid ethyl ester, methanesulfonic acid methyl ester,trifluoromethane sulfonic acid methyl ester and trifluoromethanesulfonic acid trimethylsilyl ester.

Among these, HPF₆, HSbF₆, HAsF₆, triphenyl carbonium-hexafluorophosphate and BF₃ are preferable due to the excellent activity thereof,and HPF₆ triphenyl carbonium-hexafluoro phosphate and BF₃ areparticularly preferable.

The hyperbranched polyether polyol obtained as described above ischaracterized in that a primary hydroxyl group (H1) and a secondaryhydroxyl group (H2) are included in the molecular structure thereof, anumber average molecular weight (Mn) of the hyperbranched polyetherpolyol is 1000 to 4000 and a hydroxyl value is 150 to 350 mg·KOH/g.These values are preferably in the aforementioned range, since anobtained composition has excellent flowability and can achieve excellentworkability can be achieved, and a cured product having a high hardnesscan be obtained. The hyperbranched polyether polyol is preferably usedwhen a number average molecular weight (Mn) and a hydroxyl value of thehyperbranched polyether polyol are included in the above range. However,it is further preferable that a number average molecular weight thereofis 1300 to 3500 and a hydroxyl value thereof is 170 to 330 in order toachieve the maximum effects.

That is, the hyperbranched polyether polyol of the present invention isa hyperbranched polyether polyol which has a multi-branched structureand is obtained by a ring-opening reaction between a hydroxyalkyloxetane(a1) and a monofunctional epoxy compound (a2), and therefore, thehyperbranched polyether polyol can have low viscosity since the inertiaradius thereof is smaller than the inertia radius of a generalstraight-chain polyol. Furthermore, since the number average molecularweight (Mn) of the hyperbranched polyether polyol is limited to thespecific value of 1000 to 4000, flowability can be extremely increasedto a level which has not been achieved, and therefore, it is possible togreatly improve the workability when the hyperbranched polyether polyolis used in a urethane resin composition in combination with apolyisocyanate component. When the hydroxyl value thereof is 150 to 350mg·KOH/g, the hyperbranched polyether polyol can have a lot of hydroxylgroups in spite of the small molecular weight thereof, the cross-linkdensity can increase when curing is conducted, and a hard polyurethanecured product can be obtained.

Furthermore, since the hyperbranched polyether polyol of the presentinvention has not only a primary hydroxyl group (H1) but also asecondary hydroxyl group (H2) in the molecular structure thereof, it isassumed that it is possible to achieve a long pot life due to thereaction-delay property of the secondary hydroxyl group (H2). Here, apot life should be estimated comparatively, since it can changedepending on conditions.

In the present invention, although the hyperbranched polyether polyolhas a secondary hydroxyl group which has low reactivity, it is possibleto achieve high hardness of an end cured-product, and the reasons of thecharacteristic of the present invention are supposed as follows. Thatis, the molecular structure of the hyperbranched polyether polyol canhave a three dimensional structure such as a spherical form and adendritic form due to the hyperbranched structure thereof. It isbelieved that hydroxyl groups of the three dimensional structure existsuch that they face the outside of the spherical form or the like.Therefore, it is believed that almost all hydroxyl groups can eventuallycontribute to a reaction even if the reaction rate becomes low, and thecrosslinking density of a cured product becomes extremely large. Fromthe viewpoint of balance of a pot life and hardness of a cured product,it is preferable that the number of a secondary hydroxyl group (H2) inone molecule is in a ratio of 20 to 70%, and more preferably 25 to 60%,based on the total number of all hydroxyl group in the molecule. Thetotal number of a hydroxyl group included in a molecule of ahyperbranched polyether polyol of the present invention is preferably 4or more, and more preferably 4 to 20.

The ratio of the number of a secondary hydroxyl group (H2) to the totalnumber of a hydroxyl group in a hyperbranched polyether polyol can beobtained by conducting analysis of ¹⁹F-NMR subsequent to esterificationof a hyperbranched polyether polyol using trifluoroacetic acid.

As the concrete structure of a hyperbranched polyether polyol of thepresent invention, there are various structures which can be obtained bya ring-opening reaction between a hydroxyalkyloxetane (a1) and amonofunctional epoxy compound (a2). As a concrete example, when aring-opening reaction is conducted between a hydroxyalkyloxetane (a1)represented by the following general formula (1) and a monofunctionalepoxy compound (a2) represented by the following general formula (2),the following structural unit can be generated.

(In the general formula (1), R₁ and R₂ are the same as those describedabove.)

(In the general formula (2), R₃ represents an organic residue, R₃ mayform a ring by bonding to a carbon atom, which forms an epoxy group, viaa bivalent organic residue, and R₃ may be a group which is selected fromexamples of R₂.)

That is, the aforementioned hyperbranched polyether polyol can bestructured with a structural unit which can be selected from repeatingunits and terminal end structural units which are represented by thefollowing structures.

In each structural unit shown above, a solid line represents a singlebond within the structural unit, and a broken line represents a singlebond which forms an ether linkage between the structural unit and otherstructural unit. The OR1 to OR3, OE1 and OE2 are structural unitsoriginated from a hydroxyalkyloxetane (a1), and among them, OR1 to OR3represent repeating units and OE1 and OE2 represent terminal endstructural units.

ER1, EE1 and EE2 are structural units originated from a monofunctionalepoxy compound (a2), and ER1 represents a repeating unit and EE1 and EE2represent terminal end structural units.

The repeating unit selected from the OR1 to OR3 and ER1 can form acontinuous hyperbranched structure of the hyperbranched polyetherpolyol. Furthermore, the continuous hyperbranched structure can have, atthe terminal end thereof, the terminal end structural unit selected fromthe OE1, OE2, EE1 and EE2. Here, the repeating units and the terminalend structural units may exist in any constitution, any ratio and anyamount, in so far as problems are not caused. For example, the repeatingunits and the terminal end structural units may exist randomly in thehyperbranched polyether polyol. OR1 to OR3 may construct a centerposition of the molecule structure of the hyperbranched polyetherpolyol, and the terminal end structural units may exist at the terminalends of the molecule structure. Here, a secondary hydroxyl group (H2)exists as an essential group, and therefore, EE1 exists in ahyperbranched polyether polyol as an essential unit.

A urethane resin composition of the present invention is a twocomponents type curable composition which includes a polyol component(A) and a polyisocyanate component (B). Furthermore, it is characterizedin that the polyol component (A) includes the aforementionedhyperbranched polyether polyol.

In the present invention, it is preferable that a higher fatty acidalkyl ester which has a hydroxyl group is used as well as thehyperbranched polyether polyol from the viewpoint of that hydrophobicityof a mixture wherein two liquids are mixed can be increased and foamingat the time of curing can be prevented.

Examples of the higher fatty acid alkyl ester which has a hydroxyl groupare not limited as long as problems are not caused. Examples thereofinclude; ester compounds having a hydroxyl group, which are obtained byreacting higher fatty acid such as stearic acid and linolic acid, andpolyhydric alcohol such as glycol and glycerol, so that a hydroxyl groupremains after the reaction; and ester compounds which are obtained byreacting higher fatty acid having a hydroxyl group such as recinoleicacid and a monoalcohol, glycol, glycerol, trimethylol propane or thelike; and natural fats and oils which have a hydroxyl group, such ascastor oil. These compounds may be used singly or in combination of twoor more.

Furthermore, by introducing a hydroxyl group, natural fats and oils suchas coconut oil and soybean oil, which do not have a hydroxyl group in aneffective amount, can be used as the higher fatty acid alkyl esterhaving a hydroxyl group. Such a introduction can be conducted by anester exchange reaction wherein a polyhydric alcohol is used.

Furthermore, among the higher fatty acid alkyl ester having a hydroxylgroup, those having a double bond in an alkyl chain thereof can bemodified with dicyclopentadiene in order to further improvehydrophobicity, and the modified compounds can be preferably used.

Among the higher fatty acid alkyl ester having a hydroxyl group, thosehaving a hydroxyl value of 100 to 300 mg·KOH/g and/or having the numberof carbon atoms within the alkyl chain portion thereof at 10 to 25 areparticularly preferable, since remarkable effects of hydrophobicity of acoating can be achieved.

Here, in the polyol component (A), the usage ratio of a hyperbranchedpolyether polyol to a higher fatty acid alkyl ester, which has ahydroxyl group, can be determined if necessary. It is preferable thatthe mass ratio of the hyperbranched polyether polyol to the higher fattyacid alkyl ester is 3:7 to 9:1 in order to prevent foaming. Furthermore,it is preferable that the average number of functional groups when thehyperbranched polyether polyol and the higher fatty acid alkyl ester aremixed is 4 or more from the viewpoint of increasing hardness. The upperlimit can be determined if necessary.

In the polyol component (A), another polyol can be used in combinationwith the aforementioned hyperbranched polyether polyol, in an amountsuch that the effects of the present invention does not deteriorate.Examples of another polyol include; conventionally known mono-chainpolyols such as ethylene glycol, diethylene glycol, propylene glycol,dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 3-methylpentanediol, 3,3-dimethylolheptane and trimethylolpropane; polyalkyleneether polyols which are obtained by polymerizing said mono-chain polyolsand alkylene oxides (for example, ethylene oxide, propylene oxide,butylene oxide and styrene oxide); polyester polyols which are obtainedby an esterification reaction of said mono-chain polyols and dibasicacids such as phthalic acid, maleic acid, adipic acid, tallow acid,succinic acid and hydrogenated dimer acid; a polyol type xyleneformaldehyde resin, polybutadiene polyol, polytetramethylene etherglycol and polyols which are obtained such that polyols areaddition-polymerized to epsilon caprolactone. These compounds may beused singly or in combination of two or more.

Next, a polyisocyanate component (B), which can be used in combinationwith a polyol component (A) in the urethane resin composition of thepresent invention, is explained. The polyisocyanate component (B) is notlimited as long as problems are not caused. The polyisocyanate component(B) can be used singly or in combinations of two or more kinds thereof.For example, conventional aliphatic polyisocyanates and aromaticpolyisocyanates can be used as the polyisocyanate component (B).

Here, examples of the aliphatic polyisocyanates include an alkylenediisocyanate such as hexamethylene diisocyanate (hereafter, abbreviatedto “HDI”), diisocyanate which has an alicyclic hydrocarbon structure, atrimer of a diisocyanate compound such as biuret modified HDI andisocyanurate modified HDI and an addition reaction product of HDI andtrimethylol propane.

Examples of the aromatic polyisocyanates include diphenylmethanediisocyanate (hereinafter, abbreviated to MDI), polymethylene polyphenylpolyisocyanate (hereinafter, abbreviated to polymeric MDI), tolylenediisocyanate (hereinafter, abbreviated to TDI), xylylene diisocyanate(hereinafter, abbreviated to polymeric XDI) and dimers of diisocyanatesuch as urethodione modified TDI. These compounds may be used singly orin combinations of two or more if necessary.

Among them, in order to improve the hardness of a cured product,aromatic polyisocyanates are preferable, and polymeric MDI isparticularly preferable since excellent effects for improving hardnesscan be achieved. Here, the polymeric MDI described here is obtained suchthat a high molecular product, which is obtained by polycondensation ofaniline and formalin, is isocyanated. The polymeric MDI can be used as amixture which includes MDI and another compound wherein the number ofnucleus (number of a ring) in the compound is larger than that of MDI(for example, MILLIONATE MR-200, manufactured by Nippon PolyurethaneIndustry Co., Ltd.,).

Generally, when the number of nucleus increases, the hardness of a curedproduct obtained from a composition increases but viscosity of thecomposition tends to increase. On the other hand, when the number ofnucleus decreases, compatibility of the polyisocyanate component (B)with a polyol component (A) becomes well and viscosity decreases, butstability at a low temperature deteriorates since such a aromaticpolyisocyanates is easily crystallized. Accordingly, in the presentinvention, it is preferable that the ratio of the MDI in the polymericMDI, that is, the ratio of a bifunctional component, is controlled to be50 to 80% by mass, more preferably 55 to 75% by mass, from the viewpointof the performance balance thereof. It is particularly preferable thatthe ratio is 60 to 70% by mass from the view point of prevention ofcolor spot occurrence of a coated surface, that is, from the viewpointof excellent finish.

Here, as MDI, which can be used singly as the polyisocyanate component(B) or used for controlling the number of a nucleus of polymeric MDI,there are (i) 2,2′-diphenylmethane diisocyanate (hereinafter,abbreviated to 2,2′-MDI), (ii) 2,4′-diphenylmethane diisocyanate(hereinafter, abbreviated to 2,4′-MDI) and (iii) 4,4′-diphenylmethanediisocyanate (hereinafter, abbreviated to 4,4′-MDI). These compounds maybe used singly or in combinations of two or more. When the total mass((i)+(ii)) of (i) 2,2′-MDI and (ii) 2,4′-MDI within MDI is small, thepolyisocyanate component (B) tends to crystallize at low temperature. Onthe other hand, when the total mass ((i)+(ii)) is large, it is difficultto increase the hardness of a cured product. Accordingly, it ispreferable that the mass ratio of (i) to (iii) in MDI is((i)+(ii)):(iii)=5:95 to 40:60, more preferably ((i)+(ii)):(iii)=10:90to 30:70, from the viewpoint of hardness of a cured product and lowtemperature stability of the polyisocyanate component (B).

In the present invention, when diisocyanate which has an alicyclichydrocarbon structure is used singly or in combination as apolyisocyanate (B), an obtained cured film can be hard, have moderateflexibility and have sufficient bridging property regarding cracks.Furthermore, it is possible to reduce yellowing, which is easily causedwhen aromatic polyisocyanate is used due to ultraviolet ray degradation,and to form a covering surface which is excellent in design.

Any diisocyanate which has an alicyclic hydrocarbon structure can beused as the diisocyanate without limitation, in so far as problems arenot caused. Concrete examples thereof include isophorone diisocyanate,hydrogenated xylylene diisocyanate, hydrogenated diphenyl methanediisocyanate, cyclohexane diisocyanate, norbornene diisocyanate,dimethanonaphthalene diisocyanate and polyisocyanates which are obtainedby reacting said diisocyanates with polyols. These compounds may be usedsingly or in combinations of two or more.

Here, examples of the polyols usable for the aforementioned reactioninclude alkylene diol such as ethylene glycol, diethylene glycol,propylene glycol, dipropylene glycol, tetramethylene glycol,1,3-butanediol, 3-methylpentanediol, 3,3-dimethylolheptane andtrimethylolpropane; and polyalkylene ether polyols which are obtained bypolymerizing said alkylene diol with alkylene oxide such as ethyleneoxide, propylene oxide, butylene oxide and styrene oxide. Examples ofthe polyols further include: polyester polyols which are obtained by anesterification reaction of the aforementioned alkylene diol and dibasicacid such as phthalic acid, maleic acid, adipic acid, tallow acid,succinic acid and hydrogenated dimer acid; and polyols which areobtained by copolymerization of the aforementioned alkylene diol andepsilon caprolactone.

Among the examples of the polyol, norbornene diisocyanate anddimethanonaphthalene diisocyanate are particularly preferable, since anexcellent balance of hardness and flexibility of a cured film can beachieved.

In the present invention, when the diisocyanate which has an alicyclichydrocarbon structure is used, excellent effects can be obtained. Forexample, it is possible to obtain a film which has high elongation suchthat elongation percentage of a coating is 60% or more, and is also hardsuch that a cured film has Shore hardness of D-75 or more. Accordingly,when the urethane resin composition of the present invention includesthe diisocyanate which has an alicyclic hydrocarbon structure, it ispossible to achieve reliable covering ability wherein a film canelongate sufficiently in accordance with cracks of a base substratesufficiently. Furthermore, such a urethane resin composition hasexcellent weather resistance and yellow resistance, and therefore, it ispossible to provide a covering surface which can maintain its appearanceover a long period of time.

Moreover, in the present invention, when the aforementioneddiisocyanate, which has an alicyclic hydrocarbon structure, is used asthe polyisocyanate component (B), it is furthermore possible to improveflexibility while hardness is maintained by using the diisocyanate incombination with the aforementioned higher fatty acid alkyl ester whichhas a hydroxyl group.

The urethane resin composition of the present invention is suitable as acovering material. When the urethane resin composition is used as acovering material, a target coating material can be prepared by addingfiller, and other various additives if necessary, to the polyolcomponent (A) and the polyisocyanate component (B). The coveringmaterial which is obtained from the composition of the present inventionhas show remarkable properties, for example, such that it can achievenot only a mechanical strength, as a hard covering material which canhave Shore hardness of D-75 or more, but also low viscosity andexcellent workability. That is, the urethane resin composition of thepresent invention has excellent characteristics such that the viscosityof a mixture, which is obtained by mixing the polyol component (A) andthe polyisocyanate component (B), is controlled to be 1000 mPa·s orless, more preferably 500 mPa·s or more and 800 mPa·s or less. A rollercoating or the like can be conducted when the viscosity of the mixtureis 1000 mPa·s or less. Here, the measurement of viscosity can beconducted in accordance with JISZ 8803.

A byperbranched polyether polyol and a composition of the presentinvention can be used in various methods and in various uses as long asproblems are not caused. For example, when the composition of thepresent invention is coated, examples of coating include brush coating,roller coating and spray coating. Of course, rake coating and othercoatings can be used.

Examples of the filler include calcium carbonate, surface treatedcalcium carbonate, aluminium hydroxide, precipitated barium sulfate,clay, silica and talc.

Examples of said other various additives include moisture absorbentssuch as activated alumina powder, synthetic zeolite, silica gel,diatomaceous earth, slaked lime, quicklime, magnesium hydroxide,anhydrous gypsum, calcium chloride, synthetic hydrotalcite, activatedcarbon and activated clay; organic or inorganic coloring pigments suchas azo pigments, copper phthalocyanine pigments, red iron oxide, chromeyellow, titanium oxide, zinc white and carbon black; rustproof pigmentssuch as red read, white lead, basic chromate, basic lead sulfate, zincchromate, zinc powder and MIO; and various aids such as a thixotropicagent, a leveling agent, a moisture-absorbent, silane coupling agentsand titanate coupling agents. Furthermore, if necessary, it is possibleto use a curing catalyst such as various amines and organic metalcompounds such as dibutyl tin dilaurate and dibutyl tin diacetate;plasticizer components such as dioctyl phthalate, asphalt and tar; andpetroleum based diluent component such as heavy fuel oil and aromatichydrocarbon, as long as the effects of the present invention do notdeteriorate.

The aforementioned fillers and additives can be used singly or incombination of two or more. They can be generally used by mixing themwith the polyol component (A) in accordance with conventional methods.

Various methods can be used as a method for coating a covering material,which is prepared using the composition of the present invention, ifnecessary. One example of the methods is that a polyol component (A) anda polyisocyanate component (B), and fillers and other additivecomponents if necessary, are mixed in a predetermined ratio (ordinarytemperature), and then the mixture is coated on a substrate such asconcrete, metal, plastics, FRP or a wooded substrate within a pot lifeto cure the mixture. In the present invention, it is possible to obtaina covering material which is excellent in workability since lowviscosity and sufficient pot life can be achieved. Accordingly, it ispossible to use, in addition of a trowel coating which requires skill, aroller coating, a brush coating and the like, which do not requireskill, and it is also possible to use a spray coating.

EXAMPLE

Hereinafter, the present invention is explained using Examples indetail, but the present invention is not limited only to the Examples.In the following descriptions, “parts” means parts by mass.

Here, the ratio of a secondary hydroxyl group (H2) with respect to thetotal number of a hydroxyl group in of the hyperbranched polyetherpolyols of Examples 1 to 4 and Examples 6 was measured by ¹⁹F-NMR aftera hyperbranched polyether polyol is esterified with trifluoroaceticacid.

Synthetic examples of a hyperbranched polyether polyol of the presentinvention are described below as Examples 1 to 6.

Example 1 Synthesis of a Hyperbranched Polyether Polyol

In a 500 ml three-necked flask equipped with a reflux condenser, amagnetic stirrer and a thermometer, 92.8 g (0.8 mol) of3-hydroxymethyl-3-ethyloxetane and 46.4 g (0.8 mol) of propylene oxidewere dissolved in 200 ml of dried diethyl ether, which did not includeperoxide, and then the flask was cooled at −14° C. in an ice bath.

Subsequently, a 60% by mass aqueous solution of 0.97 g of HPF₆ was addedto the mixture dropwise over 10 minutes. The reaction mixture becameslightly milky. Then, the reaction was continued at a room temperatureovernight. In the next morning, the generated transparent reactionmixture was further refluxed for 3 hours.

Subsequently, diethyl ether was removed from the obtained resin solutionby distillation, and a generated product was washed with an aqueoussolution including 2.8 g of KOH and 400 ml of water. Subsequently, theisolated organic layer was washed with 400 ml of deionized water, anddiethyl ether was removed again to obtain 136 g of a hyperbranchedpolyether polyol which was transparent and had a high viscosity. Theyield of the hyperbranched polyether polyol was 94%.

The generated hyperbranched polyether polyol had followingcharacteristics: Mn: 1390, Mw: 2520 and a hydroxyl value (hereinafter,abbreviated to OHV): 320 mg·KOH/g, and it was analyzed from proton NMRthat the ratio of 3-hydroxymethyl-3-ethyloxetane to propylene oxide was1:1 (molar basis). The ratio of the number of a secondary hydroxyl group(H2) within the total number of a hydroxyl group was 27.6%. A chart of¹³C-NMR analysis of the hyperbranched polyether polyol was shown as FIG.1, and a chart of proton NMR analysis thereof was shown as FIG. 2. Itwas confirmed that a primary hydroxyl group and a secondary hydroxylgroup existed in the molecular structure thereof.

Example 2 Synthesis of a Hyperbranched Polyether Polyol

In a 2 L three-necked flask equipped with a reflux condenser, a magneticstirrer and a thermometer, 348 g (3 mol) of3-hydroxymethyl-3-ethyloxetane and 348 g (6 mol) of propylene oxide weredissolved in 1 liter of dried diethyl ether, which did not includeperoxide, and then the flask was cooled at −14° C. in an ice bath.

Subsequently, a 60% by mass aqueous solution of 5.5 g of HPF₆ was addedto the mixture dropwise over 10 minutes. The reaction mixture becameslightly milky. Then, the reaction was continued at a room temperatureovernight. In the next morning, the generated transparent reactionmixture was further refluxed for 3 hours.

Subsequently, the reaction initiator therein was deactivated by adding a30% by mass methanol solution of 9 g of NaOMe. After filtration wasconducted, diethyl ether was removed under reduced pressure at the bathtemperature of 75° C. After diethyl ether was completely removed, 667 gof a hyperbranched polyether polyol was obtained. The yield of thehyperbranched polyether polyol was 89%.

The generated hyperbranched polyether polyol had followingcharacteristics: Mn: 1440, Mw: 3350 and OHV: 265 mg·KOH/g, and it wasanalyzed from proton NMR that the ratio of3-hydroxymethyl-3-ethyloxetane to propylene oxide was 1:1.9 (molarbasis). The ratio of the number of a secondary hydroxyl group (H2)within the total number of a hydroxyl group was 39.0%. A chart of¹³C-NMR analysis of the hyperbranched polyether polyol was shown as FIG.3, and a chart of proton NMR analysis was shown as FIG. 4. It wasconfirmed that a primary hydroxyl group and a secondary hydroxyl groupexisted in the molecular structure thereof.

Example 3 Synthesis of a Hyperbranched Polyether Polyol

In a 500 ml three-necked flask equipped with a reflux condenser, amagnetic stirrer and a thermometer, 69.6 g (0.6 mol) of3-hydroxymethyl-3-ethyloxetane and 104.4 g (1.8 mol) of propylene oxidewere dissolved in 250 ml of dried diethyl ether, which did not includeperoxide, and then the flask was cooled at −10° C. in an ice bath.

Subsequently, a 60% by mass aqueous solution of 1.46 g of HPF₆ was addedto the mixture dropwise over 10 minutes. The reaction mixture becameslightly milky. Then, reaction was continued at a room temperatureovernight. In the next morning, the generated transparent reactionmixture was further refluxed for 4 hours.

Subsequently, 300 ml of diethyl ether was removed from the resinsolution by distillation, and a generated product was washed with anaqueous solution including 2.8 g of KOH and 400 ml of water.Subsequently, the isolated organic layer was washed with 400 ml ofdeionized water twice, and then, diethyl ether was removed again toobtain a 163.2 g of a hyperbranched polyether polyol which wastransparent and low viscosity. The yield of the hyperbranched polyetherpolyol was 94%.

The generated hyperbranched polyether polyol had followingcharacteristics: Mn: 1750, Mw: 3630 and OHV: 199 mg·KOH/g, and it wasanalyzed from proton NMR that the ratio of3-hydroxymethyl-3-ethyloxetane to propylene oxide was 1:2.9 (molarbasis). The ratio of the number of a secondary hydroxyl group (H2)within the total number of a hydroxyl group was 46.3%. A chart of¹³C-NMR analysis of the hyperbranched polyether polyol was shown as FIG.5, and a chart of proton NMR analysis was shown as FIG. 6. It wasconfirmed that a primary hydroxyl group and a secondary hydroxyl groupexisted in the molecular structure thereof.

Example 4 Synthesis of a Hyperbranched Polyether Polyol

In a 500 ml three-necked flask equipped with a reflux condenser, amagnetic stirrer and a thermometer, 139.2 g (1.2 mol) of3-hydroxymethyl-3-ethyloxetane and 208.8 g (3.6 mol) of propylene oxidewere dissolved in 500 ml of dried diethyl ether, which did not includeperoxide, and then the flask was cooled at −10° C. in an ice bath.

Subsequently, a 60% by mass aqueous solution of 2.92 g of HPF₆ was addedto the mixture dropwise over 10 minutes. The reaction mixture becameslightly milky. Then, the reaction was continued at a room temperatureovernight. In the next morning, the generated transparent reactionmixture was further refluxed for 4 hours.

Subsequently, the reaction initiator therein was deactivated by adding a30% by mass methanol solution of 3.2 g of NaOMe. After the diethyl etherwas completely removed, 310 g of a viscous hyperbranched polyetherpolyol was obtained. The yield of the hyperbranched polyether polyol was89%.

The generated hyperbranched polyether polyol had followingcharacteristics: Mn: 1580, Mw: 3710 and OHV: 224 mg·KOH/g, and it wasanalyzed from proton NMR that the ratio of3-hydroxymethyl-3-ethyloxetane to propylene oxide was 1:3 (molar basis).The ratio of the number of a secondary hydroxyl group (H2) within thetotal number of a hydroxyl group was 45.0%. A chart of ¹³C-NMR analysisof the hyperbranched polyether polyol was shown as FIG. 7, and a chartof proton NMR analysis was shown as FIG. 8. It was confirmed that aprimary hydroxyl group and a secondary hydroxyl group existed in themolecular structure thereof.

Example 5 Synthesis of a Hyperbranched Polyether Polyol

In a 250 ml three-necked flask equipped with a reflux condenser, amagnetic stirrer and a thermometer, 11.6 g (0.1 mol) of3-hydroxymethyl-3-ethyloxetane and 11.6 g (0.2 mol) of propylene oxidewere dissolved in 50 ml of dried cyclohexane, and then the flask wascooled at 10° C. in an ice bath.

Subsequently, a 60% by mass aqueous solution of 0.76 g of HPF₆ (0.25mole % with respect to monomer components) was dissolved in 10 ml ofdiethyl ether, and the solution was added at once into the flask. Thereaction mixture immediately became milky. The reaction temperature ofthe mixture increased to 36° C. within one hour after the HPF₆ wasadded. Subsequently, the reaction mixture was heated to 54 to 60° C. forone hour in a oil bath and furthermore the mixture was mixed at roomtemperature overnight. Then, the reaction initiator therein wasdeactivated by adding a 30% by mass methanol solution of 0.3 g of NaOMe.The milky reaction mixture was further stirred for 4 hours until the pHof the mixture became pH6. The milky layer which was positioned as alower layer in the reaction mixture was separated, and cyclohexane wascompletely removed to obtain 18.7 g of a hyperbranched polyether polyolwhich was transparent and had low viscosity. The yield of thehyperbranched polyether polyol was 79%. The generated hyperbranchedpolyether polyol had following characteristics: Mn: 2160, Mw: 6310 andOHV: 224 mg·KOH/g, and it was analyzed from proton NMR that the ratio of3-hydroxymethyl-3-ethyloxetane to propylene oxide was 1:1.9 (molarbasis).

On the other hand, the other layer generated in the reaction mixture,that is, a transparent cyclohexane layer which was different from themilky layer, was dried to obtain 1.2 g of a hyperbranched polyetherpolyol which had low viscosity. The hyperbranched polyether polyol hadfollowing characteristics: Mn: 500, Mw: 950 and it was confirmed fromproton NMR that the ratio of 3-hydroxymethyl-3-ethyloxetane to propyleneoxide was 1:2.1 (molar basis). A chart of ¹³C-NMR analysis of thehyperbranched polyether polyol was shown as FIG. 9, and a chart ofproton NMR analysis was shown as FIG. 10. It was confirmed that aprimary hydroxyl group and a secondary hydroxyl group exist in themolecular structure.

Example 6 Synthesis of a Hyperbranched Polyether Polyol

In a 500 ml three-necked flask equipped with a reflux condenser, amagnetic stirrer and a thermometer, 58.0 g (0.5 mol) of3-hydroxymethyl-3-ethyloxetane and 106.0 g (1.5 mol) of propylene oxidewere dissolved in 500 ml of dried diethyl ether, which did not includeperoxide, and then the flask was cooled at −10° C. in an ice bath.

Subsequently, a 60% by mass aqueous solution of 1.0 g of HPF₆ (0.25 mole% with respect to monomer components) was added to the mixture dropwiseover 30 minutes. The reaction mixture became slightly milky. Then, thereaction was continued at a room temperature overnight. Then, thereaction solution was diluted with 250 ml of diethyl ether, and thenwashing was conducted with 200 ml of water three times until the etherlayer became transparent. After an organic layer was separated, theorganic layer was dried with Na₂SO₄, and ether was removed bydistillation to obtain 149.3 g of a target hyperbranched polyetherpolyol. The yield of the hyperbranched polyether polyol was 90%.

The generated hyperbranched polyether polyol had followingcharacteristics: Mn: 1540, Mw: 3200 and OHV: 178 mg·KOH/g, and it wasconfirmed from proton NMR that the ratio of3-hydroxymethyl-3-ethyloxetane to propylene oxide was 1:3 (molar basis).The ratio of the number of a secondary hydroxyl group (H2) within thetotal number of a hydroxyl group was 47.0%. A chart of ¹³C-NMR analysisof the hyperbranched polyether polyol was shown as FIG. 11, and a chartof proton NMR analysis was shown as FIG. 12. It was confirmed that aprimary hydroxyl group and a secondary hydroxyl group existed in themolecular structure thereof.

Hereinafter, examples wherein a hyperbranched polyether polyol of thepresent invention is used to prepare a polyol component are explained asReference Examples 1 to 3, and examples wherein other compound is usedto prepare a polyol component are explained as Reference Examples 4 to7.

Reference Example 1 Preparation of a Polyol Component

212 parts of the hyperbranched polyether polyol obtained in Example 2and 788 parts of castor oil wherein the hydroxyl equivalent thereof was350 were mixed to obtain a polyol component (A-1) wherein the averagehydroxyl equivalent was 316.

Reference Example 2 Preparation of a Polyol Component

120 parts of the hyperbranched polyether polyol obtained in Example 2and 880 parts of castor oil wherein the hydroxyl equivalent thereof was350 were mixed to obtain a polyol component (A-2) wherein the averagehydroxyl equivalent was 325.

Reference Example 3 Preparation of a Polyol Component

438 parts of the hyperbranched polyether polyol extracted from the milkylayer obtained in Example 5 and 562 parts of castor oil wherein thehydroxyl equivalent thereof was 350 were mixed to obtain a polyolcomponent (A-3) wherein the average hydroxyl equivalent was 256.

Reference Example 4 Preparation of a Polyol Component

A polyol component (A-4) wherein the average hydroxyl equivalent was 316was obtained such that 660 parts by weight of a castor oil having ahydroxyl equivalent of 350 and 340 parts by weight of epoxy ester havingan acid value of 0.1, a hydroxyl equivalent of 265 and a molecularweight of 936, wherein the epoxy ester was obtained by reacting 40 partsby weight of a bisphenol A type epoxy resin having an epoxy equivalentof 188 and 60 parts by weight of a castor oil fatty acid at 110° C. for15 hours under the presence of 0.2 parts by weight of triphenylphosphine while bubbling was conducted with nitrogen. Here, theaforementioned epoxy ester was different from a hyperbranched polyetherpolyol of the present invention.

Reference Example 5 Preparation of a Polyol Component

330 parts of EXCENOL 500SO (a propylene oxide addition product ofsorbitol, manufactured by Asahi Glass Co., Ltd. with a hydroxylequivalent of 112, with 6 functional groups, and a molecular weight of672) and 670 parts of castor oil which have a hydroxyl equivalent of 350were mixed to obtain a polyol component (A-5) which had an averagehydroxyl equivalent of 206. Here, the EXCENOL 500SO was different from ahyperbranched polyether polyol of the present invention.

Reference Example 6 Preparation of a Polyol Component

240 parts of EXCENOL 400 MP (a propylene oxide addition product oftrimethylol propane, manufactured by Asahi Glass Co., Ltd. with ahydroxyl equivalent of 138, 3 functional groups, and a molecular weightof 414) and 760 parts of castor oil which had an hydroxyl equivalent of350 were mixed to obtain a polyol component (A-6) which had an averagehydroxyl equivalent of 256. Here, the EXCENOL 400 MP was different froma hyperbranched polyether polyol of the present invention.

Reference Example 7 Preparation of a Polyol Component

490 parts of NIKANOL K-140 (a polyol-type xylene formaldehyde resinwhich has an aromatic ring manufactured by Mitsubishi Gas ChemicalCompany, Inc. a hydroxyl equivalent of 200, a molecular weight of 756)and 510 parts of castor oil which had hydroxyl equivalent of 350 weremixed to obtain a polyol component (A-7) which had average hydroxylequivalent of 256. Here, the NIKANOL K-140 was different from ahyperbranched polyether polyol of the present invention.

Reference Example 8 Preparation of an Isocyanate Component

100 parts by weight of commercial crude MDI (MILLIONATE MR-200,manufactured by Nippon Polyurethane Industry Co., Ltd. which includes60% by mass of polymeric MDI and 40% by mass of MDI, wherein the MDIincludes 97% by mass of 4,4′-MDI and 3% by mass of 2,4′-MDI), 26 partsby weight of MDI (LUPRANATE MI, manufactured by BASF INOAC PolyurethanesLtd., which includes 50% by mass of 4,4′-MDI and 50% by mass of2,4′-MDI) and 24 parts by weight of 4,4′-MDI (MILLIONATE MT,manufactured by Nippon Polyurethane Industry Co., Ltd.,) to prepare anisocyanate component (B).

Hereinafter, Examples 7 and 8, wherein resin compositions were producedusing polyol components which include a hyperbranched polyether polyolsof the present invention, and Comparative Examples 1 and 2 whereinpolyol components were produced using compounds which were differentfrom those of the preset invention, are explained.

Example 7

The following various evaluations were conducted using the isocyanatecomponent (B) obtained in Reference Example 8 and a compound, which wasobtained by uniformly mixing 500 parts of the polyol component (A-1)obtained in Reference Example 1, 460 parts of calcium carbonate and 25parts of pigment with a planetary mixer while vacuum degassing wasconducted, so that the rate of an isocyanate equivalent to a hydroxylequivalent was 1.15. The results were shown below.

(Evaluation Test of Mixture Viscosity and a Pot Life)

The aforementioned compound which included the component (A) and thecomponent (B) were mixed and maintained in a thermostatic water bath at25° C. After 5 minutes had been passed, the viscosity of the mixture wasmeasured with a BM type viscometer rotor No. 4 at 6 rpm, and theobtained value was determined as a mixture viscosity. Then, themeasurement was continued, and the amount of time it taken for theviscosity of the mixture to reach 50000 Pa·s was measured as a pot life.

(Evaluation Test of Film Properties)

The aforementioned compound which included the component (A) and thecomponent (B) were mixed, and a sheet was formed with the mixture. Afteraging the sheet for 70 days at a temperature of 25° C., the Shore Dhardness (JIS K-6253), the tensile strength (JIS K-6251), the elongationpercentage (JIS K-6251) and the tear strength (JIS K-6252) of the sheetwere evaluated.

(Evaluation of Surface Foaming of a Covering Surface)

A moisture-curing urethane based primer (PLYADEK T-150-35, manufacturedby DIC Corporation) was applied on a slate board, and dried to form aprimer layer. Then, the aforementioned compound, which included thecomponent (A), and the component (B) was mixed, and the mixture wasapplied on the primer layer with a trowel so that the applied amount was1.5 kg/m². The coating was cured under conditions of 35° C. and 80%, andan evaluation was conducted regarding whether or not foaming wasgenerated on the surface. Here, the evaluation was conducted by visualobservation, and when no bubbles were confirmed, it was evaluated as “nofoaming”, and when bubbles were confirmed, it was evaluated as“foaming”.

Example 8

Various performance tests were conducted n a way similar to Example 7except that the polyol component (A-2) of Reference Example 2 was used.Results were shown in Table 1.

Comparative Example 1

Various performance tests were conducted similar to Example 7 exceptthat the polyol component (A-4) of Reference Example 3 was used. Resultswere shown in Table 1.

Comparative Example 2

Various performance tests were conducted similar to Example 7 exceptthat the polyol component (A-5) of Reference Example 4 was used. Resultswere shown in Table 1.

TABLE 1 Comparative Comparative Example 7 Example 8 Example 1 Example 2Isocyanate component B B B B Polyol component A-1 A-2 A-4 A-5 Mixtureviscosity 840 790 2200 1700 (mPa · s) Pot life (minute) 54 61 59 64Shore D hardness 75 70 75 78 Tensile strength (MPa) 16.2 12.3 15.9 16.6Elongation percentage (%) 34.1 48.4 57.8 55 Tear strength (N/mm) 44.522.3 52.1 50.1 Surface foaming No foaming No foaming No foaming Foaming

As shown in Table 1, the urethane resin compositions of the presetinvention had low viscosity and were able to form a covering surfacewherein foaming was not generated even in a high temperature and a highhumidity, the surface was excellent in smoothness and they weresufficiently hard as apparent from the results of the evaluation test offilm properties. Pot life of the urethane compositions of the presentinvention were not poor as compared with that of Comparative Examples.On the other hand, in the Comparative Examples, in a case of the hardurethane covering material which included an aromatic polyol(Comparative Example 1), the prepared composition had high mixtureviscosity and did not suit a roller coating or the like. Furthermore,when linear polyfunctional polyol was used (Comparative Example 2), theprepared composition had a high mixture viscosity, and such a viscosityis not preferable since usable coating method is limited. Furthermore,foaming was occurred in the covering surface under the environment ofhigh temperature and high humidity, and therefore smoothness was poor.

Hereinafter, Examples 9 and 10, wherein resin compositions were producedusing polyol components which include hyperbranched polyether polyols ofthe present invention, and Comparative Examples 3 and 4, wherein polyolcomponents were produced using compounds which were different from thoseof the preset invention, are explained.

Example 9

Evaluations of mixture viscosity, pot life and evaluation test of filmproperties were conducted in a way similar to Example 7 using acompound, which was obtained by uniformly mixing 500 parts of the polyolcomponent (A-3) obtained in Reference Example 3, 460 parts of calciumcarbonate, 25 parts of pigment, and dibutyl tin dilaurate (625 ppm inthe compound) with a planetary mixer while vacuum degassing wasconducted, and norbornene diisocyanate (diisocyanate which has analicyclic hydrocarbon structure, hereinafter, abbreviated to NBDI) wasused so that the rate of an isocyanate equivalent to a hydroxylequivalent was 1.15. Furthermore, in accordance with the followingmethods, an evaluation test for crack bridging property and weatherresistance test were conducted. Results were shown in Table 2.

(Evaluation Test of Crack Bridging Property)

An evaluation of crack bridging property was conducted based on thequality standard test for coating material usable for concrete of JapanHighway Public Corporation. The result of the evaluation was shown suchthat ⊚ (acceptable and excellent) was shown when the crack bridgingproperty was 0.8 mm or more, a ◯ (acceptable,) was shown when the crackbridging property was 0.4 mm or more, and an X (unacceptable) was shownwhen the crack bridging property was less than 0.4 mm.

(Test of Weather Resistance)

A test sample was cut off from the sheet, which was prepared in theevaluation test of film properties, to prepare samples for a weatherresistance test. As the weather resistance test, an accelerated weatherresistance test was conducted using a sunshine weather meter(WEL-SUN-HCH-B type, manufactured by Suga Test Instruments Co., Ltd.,).The test was conducted at 63±3° C. with 18 minutes of rainfall, whichfell every 120 minutes, for 1000 hours. The color difference (ΔE) wasevaluated using a gray covering material. A color difference valueapproaching to 0 was preferable.

Example 10

Various performance tests were conducted in a way similar to Example 9except that DESMODUR W which was hydrogenated MDI (manufactured bySumika Bayer Urethane Co., Ltd) was used as an isocyanate component. Theresults are shown in Table 2.

Comparative Example 3

Various performance tests were conducted in a way similar to Example 9except that the polyol component (A-6) of Reference Example 6 was used.The results are shown in Table 2.

Comparative Example 4

Various performance tests were conducted in a way similar to Example 9except that the polyol component (A-7) of Reference Example 7 was used,and MILLIONATE MR-200 (polymethylene polyphenylene polyisocyanate,manufactured by Nippon Polyurethane Industry Co., Ltd.) was used as anisocyanate component, and dibutyltin dilaurate was not used. The resultsare shown in Table 2.

TABLE 2 Comparative Comparative Example 9 Example 10 Example 3 Example 4Isocyanate component NBDI DESMODUR W NBDI MR-200 Polyol component A-3A-3 A-6 A-7 Average number of functional 6.8 6.8 3 4 groups of (al)Mixture viscosity 520 590 390 2800 (mPa · s) Pot life (minute) 79 84 6258 Shore D hardness 75 77 55 75 Elongation percentage (%) 72.4 64.1 13431.8 Crack bridging property ⊚ ◯ ⊚ X Color difference ΔE 1.1 1 1.4 10.9

As shown in Table 2, the urethane resin composition of the presentinvention has low viscosity, can form a hard covering surface, and hasexcellent crack bridging properties. Furthermore, the urethane resincomposition of the present invention has characteristics in that theyellowing originated from ultraviolet deterioration is small, and thedesign is excellent.

On the other hand, in Comparative Examples, when the number offunctional groups and the hydroxyl equivalent of polyfunctional polyolis small (Comparative Example 3) when compared with those of the presentinvention, although crack bridging properties are excellent, it isdifficult to prepare a hard product as is apparent from the evaluationtest of film properties, for example a Shore D hardness of 55 thereof,and it cannot satisfy performances required as a hard covering material.Furthermore, when an aromatic isocyanate component and a polyolcomponent which does not include a hyperbranched polyether polyol of thepresent invention is used (Comparative Example 4), the crack bridgingproperties were poor, dense yellowing was caused in the coveringsurface, and therefore the appearance was poor, regardless of the polyolcomponent. The pot life was also poor when compared with that of thepresent invention.

INDUSTRIAL APPLICABILITY

The present invention can provide a new hyperbranched polyether polyolwhich is useful as a polyol component of a urethane resin composition,and can also provide a urethane resin composition which has excellentworkability and is suitable as a covering material which can form a hardcured product.

1: A hyperbranched polyether polyol which is obtained by a ring-openingreaction between a hydroxyalkyloxetane (a1) and a monofunctional epoxycompound (a2) in a molar ratio (a1)/(a2) of 1/1 to 1/3, wherein thehyperbranched polyether polyol has a number average molecular weight(Mn) of 1,000 to 3,500 and a hydroxyl value of 150 to 350 mg·KOH/g, andthe hyperbranched polyether polyol includes a primary hydroxyl group(H1) and a secondary hydroxyl group (H2) in the molecular structurethereof, wherein the number of the secondary hydroxyl group (H2) in onemolecule of the hyperbranched polyether polyol is in a ratio of 20 to70% based on the total number of a hydroxyl group in the molecule. 2:(canceled) 3: The hyperbranched polyether polyol according to claim 1,wherein the monofunctional epoxy compound (a2) is olefin epoxide. 4:(canceled) 5: A urethane resin composition which comprises ahyperbranched polyether polyol component (A) and a polyisocyanatecomponent (B) as essential components, wherein the polyol component (A)is a hyperbranched polyether polyol obtained by a ring-opening reactionbetween a hydroxyalkyloxetane (a1) and a monofunctional epoxy compound(a2) in a molar ratio (a1)/(a2) of 1/1 to 1/3, the hyperbranchedpolyether polyol has a number average molecular weight (Mn) of 1,000 to3,500 and a hydroxyl value of 150 to 350 mg·KOH/g, and the hyperbranchedpolyether polyol includes a primary hydroxyl group (H1) and a secondaryhydroxyl group (H2) in the molecular structure thereof, wherein thenumber of the secondary hydroxyl group (H2) in one molecule of thehyperbranched polyether polyol is in a ratio of 20 to 70% based on thetotal number of a hydroxyl group in the molecule. 6: The urethane resincomposition according to claim 5, wherein the polyisocyanate component(B) is polymeric diphenylmethane diisocyanate. 7: The urethane resincomposition according to claim 6, wherein the polymeric diphenylmethanediisocyanate includes 50 to 80% by mass of diphenylmethane diisocyanate.8: The urethane resin composition according to claim 5, wherein thepolyisocyanate component (B) is diisocyanate which has an alicyclichydrocarbon structure. 9: The urethane resin composition according toclaim 5, wherein the composition comprises a higher fatty acid alkylester, which has a hydroxyl group, in addition to the hyperbranchedpolyether polyol.